The present invention is related to an injection system adapted to be used with internal combustion engines. Specifically, the injection system measures out a combustible liquid (notably a hydrocarbide) before sending it to the injector under pressure.
In diesel engines, as well as in gasoline engines of the type with direct injection, each combustion chamber is equipped with an injector provided with an injector needle which lifts itself from a seat at the start of each injection and closes itself upon its seat as soon as the injection is terminated.
Most of the time, the injector needle is subjected to a spring applied pressure which tends to push it back upon its seat, that is, to return to its closed position. With each cycle of the injection pump, complemented or not by a distributor, the combustible liquid is introduced to the injector and the pressure wave causes the unseating of the injector needle. As soon as the pressure is reduced at the end of the injection, a spring closes the needle, and it closes it effectively most of the time. On the other hand, it can happen that the needle has the tendency to hang-up in the body of the injector so that the force of the spring becomes insufficient to effect the closing of the needle. When this occurs, communication is maintained between the body of the injector-carrier and the combustion chamber, which results in the stalling of the engine. This inconvenience is particularly grave in the case of an injection system fed by constant pressure, because then the open injector continuously furnishes the combustible fluid.
The present invention aims at avoiding this inconvenience by providing a positive system which automatically cuts off the feeding of the combustible fluid to the injector which has become stuck in an open position.